Most chronic musculoskeletal disorders such as osteoarthritis (OA) and rheumatoid arthritis (RA) require long term treatment with non-steroidal anti-inflammatory drugs (NSAIDs). The efficacy, tolerability and cost of these drugs must be weighed against their known toxicity. The American College of Rheumatology (ACR) and other consensus panels have proposed guidelines for NSAID toxicity monitoring. Factors influencing provider adoption of effective drug monitoring practices are unknown. Utilizing regional claims data from a large national insurer, United Healthcare, we propose to: 1) Define the use of both traditional and newer cyclo-oxygenase 2 (COX-2) specific NSAIDs in a population of patients unselected for adverse outcomes of these medications. 2) Describe the demographics and clinical characteristics of chronic NSAID users and their associated prescribing providers. 3) Identify potential drug-associated toxicity for NSAID users. 4) Describe the patterns and predictors of toxicity monitoring (assessment of hematologic, liver and renal function, and evaluation for hypertension) among NSAID users. 5) Use a multi-modal provider change technique to assess whether this influences the process of care for toxicity monitoring and patient level outcomes (exploratory aim) for individuals taking these agents. We will review medical records to perform toxicity monitoring determinations and also to validate administrative data-identified. To improve quality, we will define benchmarks using evidence-based guidelines and "best of care" standards for NSAID toxicity monitoring. A multi-modal quality improvement intervention utilizing provider profiles based on these benchmarks as well as a medical education program will be developed. We will test whether our interventions leads to improved process of care and patient-level outcomes for NSAID toxicity monitoring. This analysis will provide as yet unavailable knowledge about the widespread use of both new (COX-2 selective) and traditional NSAIDs in a general population and variations in NSAID toxicity and practice patterns of toxicity monitoring among a regionally based community sample. We will increase our understanding of how to change provider behavior and identify and characterize patients using claims data. This will be one of the first quality improvement studies conducted by UAB investigators working with United Healthcare. The knowledge generated from this study will lead to future large-scale investigations of both arthritis care process and outcomes of national importance.